Expanding device for pistons and plungers



S. L. McNALLY AND J. D. WILSON.

EXPANDING DEVICE FOR PISTONS AND PLUNGERS. APPLICATION TILED MAR. 2. 1920 1,398,873. Patented Nov. 29, 1921.

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S. L. McNALLY AND J. 0. WILSON.

EXPANDING DEVICE FOR PISTONS AND PLUNGERS.

APPLICATION FILED MAR Z. 1920.

Patented Nov. 29, 1921.

3 SHEETSSHEET Z S. L. McNALLY AND 1. D. WILSGN.

EXPANDING DEVICE FOR PISTONS AND PLUNGERS.

APPLICATION FILED MAR. 2.:920.

1,398,873. Paterited Nov. 29, 1921.

3 SHEETS-SHEET 3.

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STANLEY L. MCNALLY AND JOHN D. WILSON, 0F SCRANTON, PENNSSELVANIA.

ascents.

Specification of Letters Patent.

Patented Nov. 29, 1921.

Application filed March 2, 1920. Serial No. 362,735.

T 0 all whom it may concern Be it known that we, STANLEY L. Mo- NALLY and JOHN D. WILSON, citizens of the United States, residing in Scranton, Lackawanna county, Pennsylvania, have invented an Expanding Device for Pistons and Plungers, of which the following is a specification.

Our invention relates to pistons, plungers and the like, and the object of our invention is to provide improved means for expanding said pistons and plungers whereby continuous close fit may be maintained between the said pistons and plungers and the surfaces against which they operate.

In the attached drawings:

Figure 1, is a view in perspective of a grease gun provided with a plunger made in accordance with our invention;

Fig. 2, is a vertical section of the grease gun taken on the line 2--2, Fig. 3;

Fig. 3, is a horizontal section taken on the line 3-3, Fig. 2;

Figs. 4, 5, 6, 7 and 8, are detached perspectives showing the details of the plunger construction Figs. 9 and 10, are perspectives showing the cup leather packing members;

Fig. 11, is a perspective of the leather packlng ring;

Fig. 12, is a perspective of the guard ring, an

Fig. 13, is a vertical section illustrating an application of our invention to a steam pump.

W1th reference to the drawings, 1 is the cylindrical casing of a grease gun having a nozzle 2 at one end and a piston or operatmg rod 3 extending throu h an aperture in the detachable cover 1. fo the inner end of the, rod 3 is attached the piston or plunger 4, while to the outer end of the said rod 3 is secured an operating handle 5, by means of which the rod and the plunger are reciprocated. The piston 4 comprises two main plates 6 and 7, shown respectively in Figs. 4 and 5. The plate 6 has a hollow threaded extension 8 extending from one face thereof; said threaded extension being adapted to be secured in the correspondingly threaded end 3 of the rod 3. Each of the plates 6 and 7 has a raised portion 6 and 7,

respectivel of decreased diameter, in the face of which are four radial slot 9 disposed, as shown, at intervals of 90. De ressions or recesses 6" and. 7 are formed in t e center bolts or the like 11, shown in Fig. 2, whereby the two plates 6 and 7 are held together, with the radial slots of one lying coincident with the radial slots of the other.

Lying between the flanges 6 and 7 of the two plates6 and 7 and having laterally extending shanks or arms 12 established within the passages formed by the coinciding slots 9, are four segmental expanding members 12, shown most clearly in Fig. 6. The inner surfaces of these segmental members normally rest against the outer surfaces of the extensions 6 and 7 on the plates 6 and 7, as shown in Fig. 3, and a resilient split ring 13, shown in Fig. 12, extends around the outer surfaces of the members 12 and tends to hold the said members close against the said outer surface of the said extensions.

Adjacent the outer faces of each of the plates 6 and 7, and attached to said plates by the bolts 11, is a fiat disk 14; said disks being apertured at their centers to provide for the extension therethrough of the threaded extension 8 in the one case, and of a protrusion 7 upon the outer face of the plate 7 in the other case. The bolts 11 pass through these disks 14, and interposed between the said disks and the outer surfaces of the plates 6 and 7 is, in each case, a cup leather washer or packing 15. Extending around the outside of the ring 13 between the two cup leathers 15, is a leather packing ring 16; said leather ring being split, as indicated in Fig. 11, so as to permit expan sion thereof and of the ring 13.

The operating rod 3 is hollow, as clearly shown in Fig. 2, and a rod 17 extends through the said hollow rod 3, and has near the inner end threads which engage with corresponding threads upon the interior of the extension 8 of the plate 6. Upon the inner end of the. rod 17, is a substantially conical-shaped head 18 which lies in the cavity formed by the two recesses 6 and 7 in the plates 6 and 7, respectively.

As shown in Fig. 2, the inner extremities of the shanks 12 of the expanding members 12 project into the cavity occupied by the said head 18, and in the present instance the ends of the said shanks 12 are beveled so as to agree Substantially with the com head 18 upon the rod 17. Secured to the upper end of the rod 17, by threads in the present instance, is an operating handle 19, by means of which the rod 17 maybe turned to advance the latter in the threaded portion 8 and so to bring the head 18 into engagement with the extremities of the shanks 12*. In this manner, the expanding members are forced outwardly against the ring 13, thereby expanding the ring and the leather packipg 15 surrounding the ring, and causing t e said packing to bear tightly against the sides of the cylinder 1.

The outstanding features of the construction are its simplicity and strength, ease of assembling and disassembling, and provision for adjustment of the piston without the necessity of first removing the same from the cylinder or casing.

Although the invention is shown and described in the present instance in connection with a grease gun, it is to be understood that in principle the invention is capable of numerous applications, and ma extend to pistons, plungers and the like used in any connection.

As illustrative of one application other than that already described, we illustrate in Fig. 13 the application of our device to the two pistons of a steam pump. In this instance the piston rod 20 connecting the two pistons 21 and 22 is made hollow and is divided, the two ends being coupled together by a coupling 23. Each of the pistons 21* and 22 comprises two end portions 21*, 21 and 22 22 between which end portions are established the expanding sections 24 and 25 which are substantially identical in construction with the plunger hereinbefore described. The manner in which the outer portions of the pistons and the expanding section are united is clearly shown in the drawing. Extending around each of the expanding sections we have shown, in the present instance, three piston rings 26, 26, 26, substantially of the type commonly employed, and these rings may be expanded as they wear so as to bear with the desired pressure against the walls of the cylinder. The inner rods 17 and 17 which operate the expanding elements pass in each case through the respective portions of the piston rod 20, and the outer ends of the said rods 17 and 17 lie within a cavity 23 in the coupling 23. Each of the inner rods has upon its inner end a nut, 27 and 28 respectively, and the opening in the side of the coupling is such as to permit the insertion of a wrench whereby the rods may be turned to expand the piston rings upon either or both of the pistons.

We claim:

1. In a piston, the combination with a body portion comprising a pair of cylindrical plates, one of whlch has a plurality of radial slots in one face thereof, and means for holding the one plate against the slotted face of the other, of a plurality of expansion members spaced around the periphery of said body portion and having arms established in the passages formed by said slots and projecting into the cavity where the said slots meet, and means established within the said cavity and operable from the exterior of the body portion for engaging the arms to force the expansion members outwardly from the body portion.

2. In a piston, the combination with a body portion comprising two cylindrical plates, each having a recess and a plurality of radial slots formed in one face thereof, and means for holding said plates together with the said recesses and radial slots coinciding, of a plurality of expansion members spaced around the periphery of said body portion and having arms established in the passages formed by said coinciding slots and projecting into the cavity formed by said coinciding recesses, and means established within the said cavity and operable from the exterior of said body portion for engaging the said arms to force the expansion members outward from the body portion.

3. In a piston, the combination with a cylindrical body portion having a cavity in the interior thereof, of a plurality of expansion members spaced around the periphery of said body portion and having arms projecting into said cavity, means established within said cavity and operable from the exterior of said body portion for engaging the said arms to force the expansion members outward from the body portion, a disk attached to the body portion at each side thereof, and a leather packing member interposed between each of said disks and the said body portion.

4. In a piston, the combination with a cylindrical body portion having a cavity in the interior thereof, of a plurality of expansion members'spaced around the perlphcry of said body portion and hav ng arms projecting into said cavity, a resilient expansible ring extending around the outside of said expansion members and tendlng to retain the said members against the body portion, an expansible packing ring extending around said retaining ring, a disk attached to the body portion at each side thereof, a leather packing member held be-,

tween each of said disks and the respective sides of said body portion, and means established within the said cavity and operable from the exterior of said body portion for engaging the said arms to force the expan sion members outward from the body portion.

5. The combination with a cylindrical casing, of a piston adapted to reciprocate therein, said piston comprising a cylindrlcal body seaevs portion having a cavity in the interior thereof, and aplurality of expansion members spaced around the periphery of said body portion and having arms projecting into said cavity, a hollow piston rod secured to said piston and extending through one end of said casing, a threaded inner rod extending through said hollow piston rod and projeeting into said cavity, threads upon the 10 body portion of said piston engaging the threads of said inner rod, means carried by said rod adapted to engage the said arms to force the said expansion members outward from the body portion of the piston, and means upon the rod for turning the rod to bring the said arm-engaging means into engagement with said arms.

STANLEY L. MONALLY. JOHN D. WILSON.

outer end of said operating 15 

